,Fibre on aluminium line

I have a aluminium adsl line.
Fibre is available at similar speed.
Would change be of any advantage.For example with errors on current line.

Are you saying the VDSL2/FTTC estimates are identical to the ADSL estimates?

If so then it may or may not be better, i.e. until you experience and test how the errors if any impact you cannot easily predict. The checkers attempt but they can be wrong, both in good and bad ways.

Aluminium all the way to the exchange? or part way? or just from cabinet to property?

What does the checker actually state? Can you provide a link to a screen shot? And what are your current full line stats - to show your exact speeds.